Oracle
Recycle Bin
In Oracle 10g, each user has a recycle bin. If you drop a table using the traditional syntax, then by default is is cached in the recycle bin, in the user's tablespace. The name of the file starts with BIN$...; for example: BIN$NR9Won4pToa2L9UqAa9eog==$0
To drop a table without having it go to the recycle bin, use this syntax:
DROP TABLE table_name PURGE;
To empty the recycle bin, use this syntax:
PURGE RECYCLEBIN
Common Oracle system tables
Tip: Use DESCRIBE table_name to see the format of the tables.
Lists of tables
USER_CATALOG USER_TABLES ALL_TABLES USER_SYNONYMS
Lists of indexes
USER_INDEXES
Lists of columns
USER_TAB_COLUMNS ALL_TAB_COLUMNS
Lists of users
ALL_USERS
Lists of views
USER_VIEWS ALL_VIEWS
Lists of privileges
USER_TAB_PRIVS USER_COL_PRIVS USER_SYS_PRIVS